Man can't hear in a crowded restaurant.

Selective hearing is a term that commonly gets tossed about as a pejorative, an insult. When your mother used to accuse you of having “selective hearing,” she was suggesting that you paid attention to the part about chocolate cake for dessert and (perhaps purposely) ignored the part about doing your chores.

But in reality it takes an amazing act of cooperation between your brain and your ears to have selective hearing.

The Difficulty Of Trying to Hear in a Crowd

Perhaps you’ve experienced this situation before: you’ve been through a long day at work, but your buddies all insist on meeting up for dinner. They decide on the loudest restaurant (because it’s popular and the food is delicious). And you strain and struggle to understand the conversation for the entire evening.

But it’s difficult, and it’s taxing. And it’s a sign of hearing loss.

Perhaps, you rationalize, the restaurant was just too noisy. But… everyone else seemed to be having a fine go of it. You seemed like the only one having difficulty. So you start to wonder: what is it about the packed room, the cacophony of voices all struggling to be heard, that throws hearing-impaired ears for a loop? It seems like hearing well in a crowded place is the first thing to go, but what’s the reason? Scientists have begun to uncover the answer, and it all begins with selective hearing.

Selective Hearing – How Does it Work?

The scientific term for what we’re loosely calling selective hearing is “hierarchical encoding,” and it doesn’t happen inside of your ears at all. This process almost entirely takes place in your brain. At least, that’s as reported by a new study done by a team at Columbia University.

Ears work like a funnel as scientists have known for some time: they forward all of the unprocessed data that they collect to your brain. In the auditory cortex the real work is then done. That’s the part of your gray matter that handles all those impulses, translating sensations of moving air into identifiable sounds.

Just what these processes look like was still unknown in spite of the existing knowledge of the role played by the auditory cortex in the process of hearing. Thanks to some unique research methods including participants with epilepsy, scientists at Columbia were able to find out more about how the auditory cortex functions in relation to picking out voices in a crowd.

The Hierarchy of Hearing

And the insight they found out are as follows: the majority of the work done by the auditory cortex to pick out specific voices is performed by two different regions. They’re what allows you to separate and amplify particular voices in loud settings.

  • Heschl’s gyrus (HG): This is the part of the auditory cortex that takes care of the first stage of the sorting routine. Heschl’s gyrus or HG processes each unique voice and separates them into discrete identities.
  • Superior temporal gyrus (STG): At some point your brain needs to make some value based choices and this is done in the STG once it receives the voices which were previously differentiated by the HG. The superior temporal gyrus figures out which voices you want to focus on and which can be securely moved to the background.

When you have hearing impairment, your ears are missing certain wavelengths so it’s more difficult for your brain to recognize voices (depending on your hearing loss it might be high or low frequencies). Your brain can’t assign individual identities to each voice because it doesn’t have enough data. It all blends together as a result (meaning discussions will harder to understand).

A New Algorithm From New Science

It’s common for hearing aids to have features that make it easier to hear in a crowded situation. But hearing aid manufacturers can now incorporate more of those natural functions into their algorithms because they have a better idea of what the process looks like. For example, you will have a better capacity to hear and understand what your coworkers are talking about with hearing aids that assist the Heshl’s gyrus and do a little more to distinguish voices.

The more we discover about how the brain works, particularly in combination with the ears, the better new technology will be capable of mimicking what happens in nature. And better hearing outcomes will be the result. Then you can focus a little more on enjoying yourself and a little less on straining to hear.